Combustion system

ABSTRACT

A combustion system for turbine engines wherein a plurality of ejector units are placed around the circumference of an annular burner. The airflow enters the inlet pipes of the ejector units and the air flow passing through these inlet pipes pumps fuel from an annular manifold in proportion to the local air flow thereby attempting to maintain a constant fuel-air ratio around the entire annular burner where ignition occurs.

United States Patent [1 1 Chamberlain June 19, 1973 COMBUSTION SYSTEM 1,893,533 1 1933 Barber 60 3974 ux 1,918,326 7/1933 Doble 431/354 X [751 Invent chembeflam, Lake Park 2,592,748 4 1952 Sedille 60 3936 [73] Assignee: United Aircraft Corporation, East 217271358 12/1955 Owes 60/3936 X Hartford, Conn 2,948,117 8/1960 Ne rad et al. 60/3972 Filed: g- 1969 Primary ExaminerDouglas Hart 21 APPL No: 48 797 Attorney-Jack N. McCarthy 52 us. (:1. .7 60/39.74 R, 60/3936, 417/171 [57] ABSTRACT 51 Int. Cl. F02c 3/24 A combustion System for turbine engines wherein a [58] Field of Search 60/3949, 39.74, plurality of ejector units are Placed around the circum- 60/39'27 39.36 39.65, 3932; 230/92, 95 ference of an annular burner. The airflow enters the 431/354, 7; 7 7 inlet pipes of the ejector units and the air flow passing through these inlet pipes pumps fuel from an annular [56] References Cited manifold in proportion to the local air flow thereby at- UNITED STATES PATENTS tempting to maintain a constant fuel-air ratio around the entire annular burner where ignition occurs. 3,020,717 2/1962 Pearce, Jr. 60/3928 1,612,838 1/1927 Schutz 230/96 X 1 Claim, 5 Drawing Figures AIR FLOW PATENIEDJUNWW 3.739.576

coMPr sssoR COMBUSTION EXHAUST SECTION SECTION SECTION TURBINE SECTION AIR FLOW INVENTOR JOHN CHAMBERLAIN BY abzwz {f AGENT COMBUSTION SYSTEM SUMMARY OF THE INVENTION A primary object of the present invention is to provide a combustion system for turbine engines which will attempt to achieve a uniform exhaust gas temperature despite non-uniform air flow entering the combustion section. In accordance with the present invention, the uniformity of temperature is achieved by distributing the local fuel flow in proportion to the local air flow so that areas high in air flow obtain higher than average fuel flows, and areas low in air flow obtain lower than average fuel flows. This invention provides a plurality of ejector units around a common manifold through which the air fiow passes. This system provides premixing the fuel with an optimum portion of the air before it enters the burner which helps promote fast burning.

BRIEF DESCRIPTION OF THE DRAWINGS DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1 a gas turbine power plant is shown indicated generally by 1. The power plant has a compressor section 2, a combustion section 4, a turbine section 6, and an exhaust section 8. The combustion section 4 is comprised of an annular burner casing 10 with an annular burner 12 therein. A conventional fuel supply and metering control 9 provides the desired overall fuel flow to an annular manifold 11. Separate pipes 13 extend inwardly to the combustion section 4 for the ejector devices 14 to be hereinafter described.

In FIGS. 2, 3, and 4 each burner uses conventional ejector devices 14 while FIG. involves ejector devices using the vortex flow of air to create low pressure.

In FIG. 2 an annular burner casing A has an annular burner 12A therein which projects rearwardly thereof at 16. Casing 10A has an annular inner wall 15 and an annular outer wall 21 and the burner 12A has an annular inner wall 23 and an annular outer wall 25. The burner casing 10A has an annular flange 18 extending radially outwardly from the annular rear end 17 of its inner wall 15 to the inner surface of the inner wall 23 of the burner 12A and an annular flange20 extending radially inwardly from the annular rear end 19 of its outer wall 21 to the outer surface of the outer wall of the burner 12A. This construction forms an inner annular chamber 22 between the wall 23 and wall 15 and an outer annular chamber 24 between the wall 25 and wall 21. An annular partition 26 interconnects the inner and outer walls 23 and 25 of the burner 12A. Openings 28 are located in said partition 26 adjacent the walls 23 and 25 with their axes being directed so that any air flow therethrough will be directed against the walls Band 25 of the burner 12A. An annular manifold 30 is located in said burner 12A forwardly of the partition 26. The inner ends of the pipes 13 are connected to the manifold 30 so as to direct any fuel flow therethrough into said manifold.

The forward part of the burner 12 is formed as an annular slot 32, between the forward ends of the walls 23 and 25, which can receive air from the compressor section 2. A plurality of ejector units comprising an inlet pipe 34 and rear cooperating venturi section 36A are positioned within said burner 12A around its entire circumference. At each ejector location the forward ejector pipe 34 is fixed with its forward end positioned in upper and lower notches in the slot 32. The rear end of the pipe 34 is fixed in the forward wall of the manifold 30. The venturi section 36A has its forward end fixed in the rearward wall of manifold 30 and its rearward end fixed in the member 26 so that it can be positively located. The rear end of the pipe 34 is properly positioned with respect to the forward end of the venturi section 36A to obtain an ejector action. A deflector 38 is positioned in the exhaust end of each ejector unit to direct the flow outwardly against the walls. of the burner 12A. Holes 40 connect the chambers 22 and 24 to the interior of the burner 12A.

The modification shown in FIG. 3 differs from FIG. 2 in the construction of the venturi section 36A. The venturi section 36B is made shorter than the venturi section 36A of FIG. 2 and is formed having a divergent section extending rearwardly from the throat. A deflector 38B is positioned within the divergent section of the venturi section 36B and in effect forms an annular cone whichdirects the flow to a point adjacent the walls 233 and 25B of the burnerlZB.

The modification shown in FIG. 4 differs from FIG. 2 and 3 in the construction of the venturi section 36B.

The venturi section 36C is made shorter than venturi section 36B of FIG. 1 and does away with the partition 26. In this modification the outer rear end of the venturi section provides for flow of air therearound by spacing from the walls 23C and 25C of the burner 12C, at 41 and 42, and spacing from each other around the circumference of the burner 12C.

The modification shown in FIG. 5 employs a different type ejector device than the modifications shown in FIGS. 2, 3, and 4. While the annular burner casing 10D is substantially the same as in the other modifications as is the rear part of the burner 12D, the burner 12D is formed having a plurality of openings 50 at its forward end in which the ejector units 14D are placed. Each ejector unit comprises a forward cylindrical part 52 which has a cover 54 on its forward end. The rearward end of the part 52 is flanged outwardly at 56 and is fixed to the burner 12D around an opening 50. A deflector 38D is positioned within this flanged extension 56 of ejector unit 14D and directs the flow adjacent the walls of the burner as in, for example the modification shown in FIG. 3. Each plate 54 has an opening therein at its center which receives the inner end of a pipe 13 which extends in through the casing 10D. The cylindrical part 52 of the ejector unit 14D has a plurality of louvers therearound placed at an angle so as to provide a swirling effect within the unit and produce a low pressure at the center thereof so as to pull in fuel through the pipe 13 in proportion to air flow.

When the ejector unit dimensions and various flow resistances are chosen so that the fuel manifold pressure is approximately equal to the burner internal pressure, it can be shown that this system will provide excellent compensation; that is, that the local fuel flow induced will be proportional to the local air flow, making the fuelair ratio in all ejector units the same. This system would normally be designed for best compensation at a maximum fuel-air ratio.

This system is most compatible with gaseous fuels. With gaseous fuels, the system works equally well at all altitudes because the air density and fuel density vary together. With liquid fuels, the system would only work properly at one altitude.

I claim:

1. An engine having in combination, air supply means, fuel supply means, a combustion section, said combustion section having burner means, said combustion section having an inlet area for air from said air supply means, said fuel supply means including a metering control for providing a desired overall fuel flow to said burner means, said metering control directing its flow to a fuel manifold, said fuel manifold having a plurality of conduit means extending therefrom, each conduit means being connected to said burner means by an ejector unit, each ejector unit having a driving fluid inlet which receives air flow from one point in said inlet area, each ejector unit having a suction inlet connected directly to its cooperating conduit means, each ejector unit having an outlet for the mixture of said air and fuel, the amount of metered overall fuel flow being sucked into each ejector unit being dependent on the air flowing through its cooperating driving fluid inlet to maintain a substantially constant fuel-air ratio throughout, said driving fluid inlet being a cylindrical member having swirl vanes therearound to produce the low pressure for acting on the cooperating suction inlet. 

1. An engine having in combination, air supply means, fuel supply means, a combustion section, said combustion section having burner means, said combustion section having an inlet area for air from said air supply means, said fuel supply means including a metering control for providing a desired overall fuel flow to said burner means, said metering control directing its flow to a fuel manifold, said fuel manifold having a plurality of conduit means extending therefrom, each conduit means being connected to said burner means by an ejector unit, each ejector unit having a driving fluid inlet which receives air flow from one point in said inlet area, each ejector unit having a suction inlet connected directly to its cooperating conduit means, each ejector unit having an outlet for the mixture of said air and fuel, the amount of metered overall fuel flow being sucked into each ejector unit being dependent on the air flowing through its cooperating driving fluid inlet to maintain a substantially constant fuel-air ratio throughout, said driving fluid inlet being a cylindrical member having swirl vanes therearound to produce the low pressure for acting on the cooperating suction inlet. 